You’d think it would be obvious if a person you spend seven days a week with has a weight problem. Excess pounds, after all, are hard to hide. But when it comes to kids, it can be tricky to gauge when pudge is more than a passing stage or a big eater’s “healthy” appetite is anything but.

Over-reacting by focusing too heavily on food or body size can cause unnecessary worry or send the wrong message to a child, while ignoring a potential problem comes with risks, too. Childhood obesity, estimated to affect 18 percent of children, “is a serious illness and it’s a chronic illness,” says Eleanor Mackey, a child psychologist with Children’s National Health System’s Obesity Institute.

Not only does obesity increase a child’s risk for Type II diabetes – once considered solely an adult disease – it also is tied to a greater risk for heart attack, stroke and certain cancers throughout life. “There’s also evidence that [obese children] report a lower quality of life and may have more difficulty with self-esteem and depression,” says Mackey, who often finds parents are unaware of how much their child worries about weight or encounters teasing.

Even children who aren’t obese may be establishing patterns and habits that push them toward obesity — and all of its challenges — in the future. And while habits can be changed and obesity is treatable, “it’s much more easily prevented than treated,” says Mackey. She recommends these five steps for any parent worried about a child’s weight:

START WITH A DOCTOR A vital first step is checking in with your child’s pediatrician, who will know your child’s history and will be able to provide some key numbers. The most important may be BMI percentile, which is used to show a child’s BMI in relation to other children of the same age and gender. If your child’s pediatrician doesn’t provide this number – many provide height and weight percentiles on well-child visits, but not BMI percentile – ask. Like BMI measures used for adults, BMI percentile isn’t perfect since some children may be more muscular than others, but it’s the best measure we have, says Mackey.

A BMI percentile of 95 or above indicates obesity, while percentiles between 85 and 95 indicate a child is overweight. Obesity requires intervention with a medical professional, but Mackey considers anything above the 85th percentile to be a potential cause for concern. A sudden change in BMI percentile that then persists might also be an indicator that a child is trending toward obesity. Your child’s pediatrician evaluate BMI percentile patterns over time and consider other factors when determining if your child is overweight or obese.

A pediatrician can also offer dietary and exercise recommendations, and can screen for depression, anxiety or self-esteem issues.

COUNT EVERYONE IN; FOCUS ON HEALTH If you’re going to make changes with your child’s health in mind you’ll do best by making your efforts a family affair. Not only does evidence show that weight-management interventions work better when the whole family participates but counting everyone in will also help you avoid the hurt feelings that may go along with singling out one child.

You’ll also want to focus on health, rather than weight, as you incorporate changes. After all, children with a high BMI percentile may need to focus more on managing their obesity risk than children with a lower number, but “that’s not to say you shouldn’t care about good health if you don’t have a high BMI,” says Mackey.

CHOOSE YOUR WORDS CAREFULLY (OR NOT AT ALL) Though you may be tempted to have a quiet sit-down with your child about his or her weight, that may not be the best plan of action. With younger children, in particular, the best approach may be to simply begin making changes in diet and activity level without mentioning any worry about weight.

If you do feel the need to address the changes, or if your child initiates a conversation, focus on the family rather than any one individual’s weight. You might say, “We’re not doing a good job as a family of eating healthy food and I think we can do better,” or “I noticed our family seems to sit around on the couch a lot and that isn’t healthy.”

Avoid judgmental words like “skinny” or “fat” – skinny isn’t the goal; healthy is — and focus on the value of creating healthy habits rather than harping on appearance. For older children and teens, especially, that might mean linking good health with being able to do the activities they enjoy.

Studies show that people with higher self-esteem are more likely to successfully make health changes, so it’s important to foster a child’s sense of self-worth, praise them for making healthy changes and remind them they are loved. Finally, don’t tease about weight or allow teasing by other family members (siblings are sometimes the worst culprits).

MAKE HEALTHY EATING A HABIT Though we often hear the words “healthy diet,” a refresher of what that means may be in order. One good resource is The USDA’s Choose My Plate, which uses an easy-to-grasp visual to show the makeup of a healthy meal.

Mackey recommends teaching children moderation rather than banning foods outright and ensuring every meal includes fruits and vegetables. You’ll also need to keep an eye on portion control and what goes into your child between meals. “Kids snack a lot,” says Mackey. “Make sure that the quality of their snacks is high.”

A shift in perspective may be in order, too. Although it’s easy for any busy parent to fall into the habit of “just feeding them and moving on,” says Mackey, it’s best if you can view every meal as an opportunity to get good quality nutrition. That may mean changing unhealthy long-held patterns. If sugary cereals are your kids’ go-to breakfast, start building a habit around a healthier start like peanut butter on toast, says Mackey. Over time, “that can have a really big impact,” says Mackey.

For dinner, aim toward “lean and green” and create three or four easy menus you can reliably turn to in a pinch so that when you walk through the front door at 6:00 p.m., your only option isn’t to pop a frozen pizza in the oven.

And don’t forget, this is a family effort: junk food is junky for everyone. If your soccer player needs extra calories because she burns more, “make sure she’s getting healthy food,” says Mackey. “She can have bigger portions.”

MAKE MOVING A HABIT Though exercise might be a part of a weight loss program a pediatrician or other medical professional recommends, creating a formal exercise program for most kids probably isn’t the way to go. Instead, look for fun and sustainable ways to build activity into your day. Try regular evening strolls, family dance parties, walking your kids to school or making it a family challenge to always take the stairs instead of an elevator. The key is to make it a better-health habit or make it fun — preferably both. “Find things they like,” says Mackey. “If it’s something you have to force them to do, it’s not going to work in the long term.”

Antoniades is a Washington Post magazine writer, Date Lab reporter/ matchmaker — and mother of three. Follow her on twitter.

Comments our editors find particularly useful or relevant are displayed in Top Comments, as are comments by users with these badges: . Replies to those posts appear here, as well as posts by staff writers.

To pause and restart automatic updates, click "Live" or "Paused". If paused, you'll be notified of the number of additional comments that have come in.

Comments our editors find particularly useful or relevant are displayed in Top Comments, as are comments by users with these badges: . Replies to those posts appear here, as well as posts by staff writers.